Dimethyl adipate

3 Dimethyl Adipate We move to dimethyl adipate and confidently cleave the molecule in the middle to produce two identical A2X2 systems thus, we predict a deshielded triplet and a less deshielded triplet. 

To test for magnetic equivalence between HA in group 3 and HA, in group 4, we ask whether these protons couple equally with a probe proton Hx in group 2. 

One possible point of confusion should be cleared up It is often stated that chemical-shift-equivalent protons do couple with one another, but peak splitting is not observed in the spectrum. This statement is insufficient and holds only for first-order systems. But if magnetic nonequivalence is involved, the system is not first order and splitting is observed. 

The 300-MHz spectrum comes as a shock (see Fig. 4.47). Obviously, this is by no means a first-order spectrum even though A v J for the A2X2 coupling is approximately 21, assuming a J value of about 7. The equiva- 

As mentioned in Section 4.13, we treat open-chain, conformationally mobile compounds as systems in which the protons in each set are magnetic equivalent to each other, at least in practice, because of near averaging of the coupling constants. The same treatment was accorded to the present molecule the system was thus presented as X2A2A2X2, and we erred in cleaving between two strongly coupled A2 sets. How then do we treat the system  

What we have in the symmetric molecule dimethyl adipate is an extreme case of strong coupling between the sets labeled A2, for which Av/J is zero. That is, the protons of the A2 sets are chemical-shift equivalent and couple as a conglomerate with the X2 protons. This is another example of virtual coupling. 

Ha and Ha. do not couple equally with Hx, for example the HAHX coupling involves 3 bonds, whereas 

It may be useful at this point to recapitulate briefly the requirements for a first-order system  

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Reduction. Hydrogenation of dimethyl adipate over Raney-promoted copper chromite at 200°C and 10 MPa produces 1,6-hexanediol [629-11-8], an important chemical intermediate (32). Promoted cobalt catalysts (33) and nickel catalysts (34) are examples of other patented processes for this reaction. An eadier process, which is no longer in use, for the manufacture of the 1,6-hexanediamine from adipic acid involved hydrogenation of the acid (as its ester) to the diol, followed by ammonolysis to the diamine (35). 

CO, and methanol react in the first step in the presence of cobalt carbonyl catalyst and pyridine [110-86-1] to produce methyl pentenoates. A similar second step, but at lower pressure and higher temperature with rhodium catalyst, produces dimethyl adipate [627-93-0]. This is then hydrolyzed to give adipic acid and methanol (135), which is recovered for recycle. Many variations to this basic process exist. Examples are ARCO s palladium/copper-catalyzed oxycarbonylation process (136—138), and Monsanto s palladium and quinone [106-51-4] process, which uses oxygen to reoxidize the by-product... 

The first CO route to make adipic acid is a BASF process employing CO and methanol in a two-step process producing dimethyl adipate [627-93-0] which is then hydroly2ed to the acid (43—46). Cobalt carbonyl catalysts such as Co2(CO)g are used. Palladium catalysts can be used to effect the same reactions at lower pressures (47—49). 

Indole and indoline alkaloids —C(0)(CH2)4C02CH3 from dimethyl adipate (CH30C(0)C=CHC(0)CH3)... 

Diesters dimethyl malonate, dimethyl succinate, dimethyl glu-tarate, and dimethyl adipate... 

The submitter prepared the material from dimethyl adipate following the procedure published by Pickney for the diethyl ester. The checkers obtained their material by fractional distillation of mixed carbomethoxy- and carbethoxycyclo-pentanone available from Arapahoe Chemical Co., Boulder, Colorado. 

The same catalyst system was applied to the condensation of racemic a,a -dimethyl-l,4-benzenedimethanol and dimethyl adipate. Optically active polyesters (Mw = 3400g/mol Mn = 2100g/mol) were obtained [24] (Scheme 1.18). 

By this approach, esters such as di(2-ethylhexyl) adipate and an oligomeric ester of neopentyl glycol have been synthesized recently by alcoholysis of dimethyl adipate ester and the corresponding alcohols, with alkaline earth metal compounds as the catalysts (171) (Scheme 30). These types of esters find application as lubricants, and it is suggested that they can be used as environment-friendly substitutes for petroleum-derived lubricants. The reactions were carried out with isooctane as a... 

One process that capitalizes on butadiene, synthesis gas, and methanol as raw materials is BASF s two-step hydrocarbonylation route to adipic acid(3-7). The butadiene in the C4 cut from an olefin plant steam cracker is transformed by a two-stage carbonylation with carbon monoxide and methanol into adipic acid dimethyl ester. Hydrolysis converts the diester into adipic acid. BASF is now engineering a 130 million pound per year commercial plant based on this technology(8,9). Technology drawbacks include a requirement for severe pressure (>4500 psig) in the first cobalt catalyzed carbonylation step and dimethyl adipate separation from branched diester isomers formed in the second carbonylation step. 

Following hydrogenation over palladium on carbon(33), dimethyl adipate hydrolysis to adipic acid is carried out using a strong mineral acid such as sulfuric acid. Hydrolysis is nearly quantitative with a selectivity of 99.5%. Since the adipic acid from the oxycarbonylation process contains no branched by-product acids, as is the case with the commercial oxidation process, extensive recrystallization is not required to produce a polymer grade material. Results indicate that the dried adipic acid crystals contain less than. 5 weight % moisture and are 99.95 weight % pure on a dry basis. 

Direct use of dimethyl adipate from the oxycarbonylation process to produce nylon 6,6 could be an attractive alternative to current adipic acid/nylon 6,6 technology. Dimethyl adipate condensation with hexamethylene diamine would give methanol rather than water. Reactors, which currently use caprolactam to prepare nylon 6, could also easily be retrofitted to produce nylon 6,6. Dimethyl hex- nedioate or dimethyl adipate are also useful raw materials for preparation of other high volume chemicals including hexamethylene diamine, caprolactam, and 1, -hexanediol. 

In order to keep polyamides soluble in relatively apolar solvents, the use of flexible (macro)monomers such as a, co-(diaminopropyl)polydimethylsiloxane [52] or oligoethyleneglycol-based diamines [53, 54] has been proven to be a successful approach (Fig. 10). Poly condensations of dimethyl adipate with a variety of diamines were successful in bulk and at moderate temperatures between 60 and 100 °C (reaction A in Fig. 10). The low temperatures (60-100 °C) that suffice in these polymerizations also allow the use of monomers that are thermally instable, such as diethyl fumarate [53]. Moreover, multifunctional amines could be regioselectively polymerized up to molecular weights of 9 kDa, making lipase catalysts a valuable tool for the preparation of well-defined polyamides that can be further functionalized with active groups. 

While all previous examples employ enzymatic ROP, there are two reports on block copolymer synthesis employing enzymatic poly condensation. The first one was published by Sharma et al. and describes the synthesis and solid-state properties of polyesteramides with poly(dimethylsiloxane) (PDMS) blocks [21]. The polycondensation was carried out with various ratios of dimethyl adipate. 

Hilker et al. successfully employed the DKR of secondary alcohols developed at the Dutch company DSM [100] to prepare chiral polymers from a, a -dimethyl-1,4-benzenedimethanol (1,4-diol) and dimethyl adipate (DMA) (Fig. 12a) [101]. 

Fig. 12 (a) DKR polymerization of 1,4-diol and dimethyl adipate, (b) Chemical structure of Noyori-type racemization catalyst 1 and Shvo s racemization catalyst 2... 

A good example of template copolycondensation has been described by Ogata et al Copolycondensation of 2,6-dimethyl pyridine dicarboxylate and dimethyl adipate with hexamethylene diamine was carried out in the presence of polysaccharide - Pullulane (mol. weight 30,000) used as a template. The reaction was carried out in DMSO at 60 C. It was found that the content of 2,6-dimethyl pyridine dicarboxylate units in the copolyamide, determined by NMR analysis, increased in the presence of Pullulane in comparison with the amount obtained in the absence of the template. This effect can be explained by preferential adsorption by the template of monomer having pyridine groups in comparison with the adsorption of dimethyl adipate. A set of experiments was carried out under the same conditions, but in the presence of poly(acrylonitrile) instead of Pullulane. The composition of copolyamides was the same as in copolycondensation without the template. 

Carboxylation of dienes and trienes, which takes place in a stepwise fashion, affords mono- or dicarboxylated products.146 Cobalt carbonyl,147 palladium chloride,148 149 and palladium complexes150 were used. 1,4 Addition to 1,3-butadiene gives the corresponding unsaturated tram ester (methyl trans-3-pentenoate) in the presence of [Co(CO)4]2 and a pyridine base.147 The second carboxylation step requires higher temperature than the first one to yield dimethyl adipate. In a direct synthesis (110°C, 500 atm, then 200°C, 530 atm) 51% selectivity was achieved.147... 

Glularic Acid. Until 1990-1991 glularic acid was available commercially from DuPont as a by-product in the production of adipic acid. It is no longer available, but DuPont produces dimethyl glutaratc and mixtures of dimethyl succinate and dimethyl glutarate. as well as mixtures of dimethyl glutarate and dimethyl adipate. 

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